Four hundred forty-one subjects 34 to 69 yr of age were recruited from a random sample of the community. They answered a questionnaire and were monitored in their homes for sleep-disordered breathing (SDB). This report concerns the association between observed SDB and arterial hypertension and vascular disease. Hypertension was defined as self-report of a diagnosis of hypertension made by a physician, current treatment for hypertension, or a systolic pressure greater than 150 mm Hg or a diastolic pressure greater than 90 mm Hg. Coronary artery disease was defined by self-report of angina or myocardial infarction of "heart attack." There were few cases of stroke or claudication, and a category of "occlusive vascular disease" was defined by self-report of coronary artery disease or of "blocked arteries" or stroke. Subjects were classified as snorers (n = 289) or nonsnorers (n = 73) by self-report of regular snoring, and as having SDB (n = 79) if more than 15 abnormal respiratory events were recorded per hour of recording. There were significant increases in the prevalence of hypertension, coronary artery disease, and occlusive vascular disease from nonsnorers (26, 7, and 10%, respectively) through snorers (39, 12, and 17%) to subjects with SDB (57, 20, and 28%). The crude odds ratio for SDB versus nonsnorers was 3.8 (95% CI, 1.9 to 7.5) for hypertension, 3.5 (1.2 to 10.0) for coronary artery disease, and 3.7 (1.5 to 9.1) for occlusive vascular disease.(ABSTRACT TRUNCATED AT 250 WORDS)